What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
1Scandinavian Mythology= frost giant.
2Astronomy. A giant planet, such as Uranus and Neptune, whose interior is thought to contain a significant proportion of water, methane, and other normally volatile compounds in condensed forms.
Mid 19th century; earliest use found in Encyclopedia Americana. From ice + giant.